What if the Confederacy had won the American Civil War? It’s July 1864 and three oh-so-young Union troopers are assigned to a mountaintop in Tennessee to be a link in a chain of flag signalers across a ridge of mountains. They encounter a dizzying gorge with a rickety bridge, bears, aching heartache, freezing cold, avalanche, bats, skeletons, deserted cabins, puzzling mysteries, starvation, and more.